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We Measure the Shortest Shadows of the Year!

One of the pluses of swimming Masters at noon is that we get to observe the sun's transit on a daily basis. [The sun's transit is its highest point in the sky each day. Throughout the year, this usually occurs sometime between 12:00 Noon and 1:20 PM — depending on whether we're on standard or daylight time.]

This time of year (Solstice time), the sun marks its transit at approximately 76º high in the sky at our latitude. Today this occurred at about 1:09 PM for our location (according to my celestial data app). [Stanford's latitude is 37.42º. Subtract from that number 23.5º which is the earth's tilt = 13.92º. Subtract 13.92º from 90º (directly overhead) and you get approximately 76º.]

For the second straight year, Noon Masters observed this passage. Rocket scientist Steve Fuselier (right) and I (left) measured a vertical poolside pole and the length of the shadow it casts at 1:09 PM. Having two sides of a right triangle, we then did a simple trigonometry calculation (tan-1) to determine the sun's height at its transit. According to our crude measurements, we calculated about 76º+. So, we were pretty close.

What does this all mean? If you swim at noon, you get the shortest shadows of the day. And today's was the shortest of the year!

As Carl Spackler would say: "So we've got that going for us . . . which is nice." [Make sure you check out this video]

Comments

And was the shadow length the same as last year's?

On direct axis from our house, on the Solstice, the Sun sets directly over Teton Pass - exactly there - except for minor perturbations from year to year since the earth does wobble a bit (perhaps from imbibing too much oil?).

This year the sun hit spot on! We thus concluded that the earth has not flipped on its axis, and enjoyed a glass of fine Zinfandel in celebration.

Yes, as Carl Spackler would say: "so we've got that going for us..which is nice."